"Price Tracker" is a Node.js app that can be used to obtain the rates of many different symbols at different exchanges. This includes normal currencies, crypto currencies, gold/silver prices, and so on.
It uses Redis to store data, and cheerio (server-side jQuery) for scraping.
Everything is accesible via both REST and WebSockets APIs.
Returns the list of supported exchanges, and supported symbols in each exchange.
Request:
GET /api/v1/exchanges
Example:
$ curl http://localhost:5000/api/v1/exchanges
{
"data": [
{
"exchange": "ambito",
"symbols": [
"USDARS",
"USDARSB"
]
},
{
"exchange": "kraken",
"symbols": [
"BTCUSD",
"LTCUSD"
]
},
[...]
]
}
Returns the list of supported symbols, and the exchanges that provide them.
Request:
GET /api/v1/symbols
Example:
$ curl http://localhost:5000/api/v1/exchanges
{
"data": [
{
"symbol": "XAUUSD",
"exchanges": [
"bullionvault"
]
},
{
"symbol": "USDARSB",
"exchanges": [
"ambito",
"cronista"
]
},
{
"symbol": "BTCUSD",
"exchanges": [
"kraken",
"bitfinex",
"bitstamp",
"coinbase",
"okcoin"
]
},
[...]
]
}
Returns the information for this symbol in this particular exchange.
Request:
GET /api/v1/symbols/<symbol>/<exchange>
Fields:
- exchange: Name of the exchange/source
- symbol: Symbol name
- bid: Best buy offer
- ask: Best sell offer
- updated_on: Date in which this information was retrieved from the exchange (it may have been retrieved recently but the data could still be old)
- custom: Additional data, depending on symbol/exchange
- volume24: Total volume transacted in the last 24 hours
- high24: Highest sell value in the last 24 hours
- low24: Lowest sell value in the last 24 hours
- published_on: Date in which this information was published (this is the real date, but it's not always available)
- stats: Additional info generated from historical data
- last_change: Date of last registered price change
- daily: Daily OHLC
- date: Period starting date
- bid:
- open: Period opening bid price
- high: Period highest bid price
- low: Period lowest bid price
- closing: Period closing bid price
- ask:
- open: Period opening ask price
- high: Period highest ask price
- low: Period lowest ask price
- closing: Period closing ask price
Example 1:
$ curl http://localhost:5000/api/v1/symbols/BTCUSD/bitstamp
{
"data": {
"exchange": "bitstamp",
"symbol": "BTCUSD",
"bid": 248.15,
"ask": 248.35,
"updated_on": "2015-06-27T20:55:54.519Z",
"custom": {},
"stats": {
"last_change": "2015-06-27T20:55:54.519Z",
"daily": {
"date": "2015-06-27T00:00:00.000Z",
"bid": {
"open": 242.98,
"high": 249.18,
"low": 242.36,
"close": 248.15
},
"ask": {
"open": 243.01,
"high": 249.62,
"low": 242.37,
"close": 248.35
}
}
}
}
}
Example 2:
$ curl http://localhost:5000/api/v1/symbols/USDARSB/cronista
{
"data": {
"exchange": "cronista",
"symbol": "USDARSB",
"bid": 13.4,
"ask": 13.6,
"updated_on": "2015-06-27T20:56:14.129Z",
"custom": {
"published_on": "2015-06-25T03:00:00.000Z"
},
"stats": {
"daily": {
"date": "2015-06-27T00:00:00.000Z",
"bid": {
"open": 13.4,
"high": 13.4,
"low": 13.4,
"close": 13.4
},
"ask": {
"open": 13.6,
"high": 13.6,
"low": 13.6,
"close": 13.6
}
}
}
}
}
Returns all stored prices for this particular symbol in this exchange in the specified date range.
Request:
GET /api/v1/symbols/<symbol>/<exchange>/series?start=<start>&end=<end>
Fields:
- exchange: Name of the exchange/source
- symbol: Symbol name
- series: List of elements with the following fields:
- date: Period start date
- bid: buy offers OHLC for this period
- ask: sell offers OHLC for this period
Example:
$ curl http://localhost:5000/api/v1/symbols/USDARSB/cronista/series
{
"data": {
"exchange": "cronista",
"symbol": "USDARSB",
"series": [
{
"date": "2015-06-17T00:00:00.000Z",
"bid": {
"open": 12.6,
"high": 12.75,
"low": 12.6,
"close": 12.75
},
"ask": {
"open": 12.8,
"high": 12.95,
"low": 12.8,
"close": 12.95
}
},
{
"date": "2015-06-18T00:00:00.000Z",
"bid": {
"open": 12.75,
"high": 12.78,
"low": 12.75,
"close": 12.78
},
"ask": {
"open": 12.95,
"high": 13.08,
"low": 12.95,
"close": 13.08
}
}
]
}
}
var ws = new WebSocket(host);
// Using plain objects:
ws.onopen = function (event) {
ws.send('{
"type": "ExchangesRequest",
"request": {
"options": {}
}
}');
ws.send('{
"type": "SymbolRequest",
"request": {
"symbol": "LTCUSD",
"exchange": "kraken",
"options": {}
}
}');
};
// Or, using classes:
ws.onopen = function (event) {
ws.send((new ExchangesRequest()).toString());
ws.send((new SymbolRequest("LTCUSD", "kraken")).toString());
};
ws.onmessage = function (event) {
var object = JSON.parse(event.data);
if (object.type == "Exchanges") {
object.response.data.forEach(function(item) {
item.symbols.forEach(function(symbol) {
console.log("exchange:", item.exchange, "symbol:", symbol);
});
});
} else if (object.type == "Symbol") {
console.log("symbol:", object.response.data.symbol);
console.log("exchange:", object.response.data.exchange);
console.log("bid:", object.response.data.bid);
console.log("ask:", object.response.data.ask);
}
};
- Install node:
Ubuntu: $ sudo apt-get install npm
macOS: $ brew install node
- Install dependencies:
$ npm install
- Run Redis: install from source (https://redis.io/download) or run it inside a container:
$ docker run -d -p 6379:6379 redis
- Start the server:
$ node server.js
The server will be ready to accept connections at http://localhost:5000. Try with:
$ curl http://localhost:5000/api/v1/symbols/BTCUSD/bitstamp
The application can be previewed live at http://price-tracker.herokuapp.com/
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